This invention relates to an ink jet system printer wherein ink drops issuing at a constant rate from a nozzle are charged in accordance with charging signals and then deflected in accordance with the charges carried by the drops as they pass through a fixed electric field, thereby to form images representative of input signals, and more particularly to an improved printer and its associated control circuit system for minimizing the occurrence of printing distortions due to air resistances acting on the charged ink drops in their path toward the record receiving member.
In a U.S. Pat. No. 3,596,275 granted to Richard G. Sweet there is disclosed an ink jet system printer of the charge amplitude controlling type wherein ultrasonic vibration is applied to ink fluid issuing under pressure from a nozzle to form ink drops at a predetermined rate and the ink drops are charged in accordance with the charging signals and then the charged ink drops are electrostatically deflected to modify their respective trajectories in accordance with the amplitude of the charges on the drops so that symbols corresponding to the charging signals are recorded on a record receiving member such as paper.
In such charge amplitude controlling type of ink jet system the ink drops issuing from the nozzle and traveling toward the record receiving member are under the influence of air resistance. The air resistances having the influence on individual charged ink drops are dependent upon the trajectories of the preceding charged ink drops and the spacing away from the preceding charged ink drops. In particular, since the trajectories of the charged drops serving for printing purposes are varied, the air resistance values exerted on these charged drops are varied and this variation depends upon the presence or absence of charged drops immediately preceding them. Moreover, the differences in the air resistance are remarkable especially in the case of high velocity printing where the ink drops are rapidly traveling. These differences in the air resistance value appear as the extent of deflection on the record member and cause the faulty printing.